Let x0 of type ι be given.
Let x1 of type ι → ι → ι be given.
Let x2 of type ι → ι → ι be given.
Assume H0: ∀ x3 . x3 ∈ x0 ⟶ ∀ x4 . x4 ∈ x0 ⟶ x1 x3 x4 = x2 x3 x4.
Let x3 of type ο → ο → ο be given.
Apply prop_ext with
explicit_Group x0 x1,
explicit_Group x0 x2,
λ x4 x5 : ο . x3 x5 x4.
Apply explicit_Group_repindep with
x0,
x1,
x2.
The subproof is completed by applying H0.